The development of wireless charging technology has progressed rapidly in recent years. Wireless charging, as opposed to wired charging, improves durability and longevity of the charging components by limiting contact and exposure of the components, increases safety by concealing potentially dangerous wires and connection interfaces, and enhances versatility by allowing charging stations to be implemented in a variety of ways (e.g., as a portable charging pad, embedded in a parking lot or road, etc.).
Wireless charging relies on an electromagnetic field to transfer energy between a charging station (wireless charging assembly) and an electronic device, such as a smart phone, a laptop, an electric vehicle, or the like. Energy is transmitted through an inductive coupling formed between the wireless charging assembly and the device. Typically, an induction coil in the wireless charging assembly (transmitting or primary coil) uses alternating electric current, often provided from the power grid, flowing through the coil to create an alternating electromagnetic field. When an induction coil in the electronic device (receiving or secondary coil) is positioned within the generated electromagnetic field, a current is induced in the coil, and the device converts the induced current into direct current to charge its battery. As a result, the transmitting and receiving induction coils combine to form an electrical transformer, whereby energy can be transferred between the two coils through electromagnetic induction.
A key element of successful wireless energy transfer typically requires that the wireless charging assembly and the electronic device be located within reasonable proximity to one another. With respect to the wireless charging of vehicles, for example, the receiving coil installed in an electric vehicle (EV) or hybrid electric vehicle (HEV) must be satisfactorily aligned with the transmitting coil of the wireless charging assembly in order for the vehicle to be effectively charged. Though recent methods, such as resonant inductive coupling, allow for the wireless charging assembly and electronic device to be spaced further from each other, wireless energy transfer efficiency can suffer if the coils are misaligned, even when using such techniques. Generally speaking, as the transmitting and receiving coils are spaced further apart, and misalignment between the coils increases, energy loss increases, causing charge efficiency to suffer.